John Calvin Commentary Jeremiah 48:36

"Therefore my heart soundeth for Moab like pipes, and my heart soundeth like pipes for the men of Kir-heres: therefore the abundance that he hath gotten is perished." — Jeremiah 48:36 (ASV)

Here the Prophet, as has been stated before, does not mourn the calamity of the people of Moab. Instead, he assumes the character of others so that the event might appear more evident, being set, as it were, before our eyes. For, as we have said, the wealth of the Moabites was so great at that time that it dazzled the eyes of all.

It was then difficult for the faithful to conceive of this vengeance of God. Therefore, the Prophet takes on the feelings of others and relates what the Moabites would do when God had so severely afflicted them.

My heart, he says, shall sound like pipes. Some think that mournful pipes are meant, but I do not know whether or not they were instruments of this kind. And there are those who think that חללים, chellim, were bagpipes, but I leave aside what is too refined.

The Prophet simply means that the trepidation would be so great that the hearts of the Moabites would make a noise like pipes. He repeats the same thing in different words: that his heart would make a noise, or sound, for the men of Kir-heres, about which city we spoke yesterday.

He now adds, for the residue which they have made, or which Moab has made (for the verb is in the singular); and then, they have perished, where there is also a change of number. But the reference is to the word “residue,” יתרת, iteret, which included hidden treasures, as we have stated.

Therefore, whatever the Moabites had gained for themselves, and whatever they thought would always be safe, the Prophet declares that it would perish. Isaiah adds, “their substance,” פקותם, pekotem, and says that they would carry it to the willows, that is, to deserted places. This is as though he had said that all the wealth of the Moabites would be scattered, as though it were, as they say, a thing forsaken.